There's no substitute for inches....

[kerryg]

Came across this on the www.howstuffworks.com and and thought it was interesting. The Bugatti Veyron puts out 1001 hp from 8 litres by running 4 turbo chargers with boost up to 18psi to increase the amount of air stuffed into each cylinder and so gets the same hp out of a 8 litre engine as from a 16 litre normally aspirated engine. But there's some interesting numbers. Wouldn't wanna pay for the gas in the Bugatti...

If you want to create a 1,000-horsepower engine, it has to be able to burn enough gasoline to generate 1,000 horsepower. That works out to about 1.33 gallons (5 liters) of gasoline per minute.

How much gas is that?
Here's a quick calculation, which you can ignore if you hate math:
1,000 horsepower is equivalent to roughly 2.6 billion joules per hour. A gallon (3.8 liters) of gasoline contains 132 million joules, so a 1,000-hp engine has to be able to burn just over 20 gallons of gasoline per hour.
However, car engines are only about one-quarter efficient -- three quarters of the gasoline's energy escapes as heat rather than as power to the wheels. So the engine actually has to be able to burn at least 80 gallons per hour, or 1.33 gallons (5 liters) per minute.
Let's convert over to metric. Gasoline requires about 14.7 kilograms of air to burn 1 kilogram of gas. Air weighs 1.222 kilograms per cubic meter at sea level. A gallon of gasoline weighs 2.84 kilograms. So the engine has to be able to process 2.84*1.33*14.7 kilograms of air per minute, or roughly 45 cubic meters of air per minute. That's 45,000 liters of air per minute.
If a V-8 engine is turning at 6,000 rpm, it can inhale a total of 24,000 cylinders' full of air per minute. If it needs to inhale 45,000 liters of air per minute, it works out to roughly 2 liters per cylinder-full. That's a 16-liter engine.



We need a 16-liter engine to burn 1.33 gallons of gas per minute. That actually makes sense -- the engine in the Dodge Viper is 8.0 liters in displacement and produces 500 hp

[marty]

i'm sure 4 turbos could stuff a fair bit more air in than a crappy old 8L viper motor though

[bungbung]

I would like to see someone with a 1000hp or even 500hp car use all of their power for oneminute non-stop.

A few years back I had a turbo'ed Subaru, the ECU had a learning mode which required full boost for 30secs. Finding somewhere to do that was tricky, ended up trying Ngaraunga Gorge 4th gear dragging the handbrake...

[vifferman]

The mathematics is slightly off - it doesn't allow for overfilling of cylinders, or for the fact that most high-performance engines (like motorcycle engines) can rev to more than the lowly figures of Detroit Iron. The 1-litre MotoGP bikes turn out 250 HP fairly readily, with normal aspiration.

I believe the record for normally-aspirated petrol engines is still held by a 1960s Honda 50 racer: 17hp, which is 340hp/litre.

[Marmoot]

Basically, for the same engine, if you run a boost of 16psi or 1bar (with a turbo or supercharger) you basically double your engine capacity. And if we asume 100% efficiency (ideal situation) you will end up with twice the horsepower rating that you have.

Other major things that determine horsepower: rpm limit (that's why pocket rocket bikes can do similar or more hp as family sedan), compression ratio (that's why big hp racecar often blow up their heads) and cylinder head design.

[Jamezo]

why don't they focus some more on enhancing efficiency? I had an idea a while back for multi-cylinder engines, tell me if I'm not being original:

In your standard V8, as far as I am aware, the cylinders are 180 degrees out of phase with each other, the models I have seen have at maximum stroke on one bank: out-in-in-out, and in the other bank in-out-out-in.

Surely this is an inneficient arrangement, I envisage an engine where each group of two cylinders is out by 45 degrees on the camshaft (this would require counterbalances at each cam connection, or else the entire cam would be unbalanced: as viewed down the shaft (without counterbalances) it would look like: _\|/ (45 degree angles though) so it would shake itself to bits without them)

This lets a cylinder fire every 45 degrees of cam rotation (well, not fire, it's a 4 stroke, but ya know what I mean), as opposed to 180 degrees, potentially giving an enourmously smoother engine (4x when you think about it)

This might have presented problems in the past, but with modern valve-timing technology, it should be fairly straightforward.

Only downside? V8's might not rumble like they used to, they would just puuurrrrrrrr. mmmmmm.

[Marmoot]

Because V8 concept is actually a "supersized V4".
If you are talking about rev and smooth engine, you'd be looking at those inline 6 (Supras, Skylines). Or, if you want something that's smooth and big then it's gotta be a V8 or V12 Ferraris

Also, while we're on that topic, why Ferrari can achieve high horsepower on a naturally aspirated engine is mostly because most of their 4litre plus engine revs their tits off until 9000rpm.
You'll never see a Holden on a 9000rpm....

[Coyote]

I believe the record for normally-aspirated petrol engines is still held by a 1960s Honda 50 racer: 17hp, which is 340hp/litre.

How fast does this 50 go?

[speedpro]

Because V8 concept is actually a "supersized V4".
If you are talking about rev and smooth engine, you'd be looking at those inline 6 (Supras, Skylines). Or, if you want something that's smooth and big then it's gotta be a V8 or V12 Ferraris

Also, while we're on that topic, why Ferrari can achieve high horsepower on a naturally aspirated engine is mostly because most of their 4litre plus engine revs their tits off until 9000rpm.
You'll never see a Holden on a 9000rpm....

Straight sixes - yummy - Mk3 zephyrs, Nissan RB20 & 25s, Honda CBX, beautiful and what a nice sound. I hate the 4-pot thing I have now.

Actually anything with a multiple of 3 cylinders sounds great I think, like Tridents, Rocket 3s and XS750 & 850s, car (straight)6s and V12s or a Merlin engine going for it.

[Zapf]

sounds like I need to bring a I6 to a KB ride :P

[FzerozeroT]

wouldn't a turboed car bemore energy efficient at max horsepower? less area of the cylinder walls for heat to escape thru so more heat into gas - more expansion - more power, hell if you wanted to really reduce the amount of heat lost you could plate the cylinder walls with something like nickasil(sp) :P

[Marmoot]

wouldn't a turboed car bemore energy efficient at max horsepower? less area of the cylinder walls for heat to escape thru so more heat into gas - more expansion - more power, hell if you wanted to really reduce the amount of heat lost you could plate the cylinder walls with something like nickasil(sp) :P

Turboed car is always more efficient than normal N/A

And, please now, don't go into those kwaka150 nickasil electroplating thingy....LOL....next you'll be talking about KIPS and SuperKIPS
Hey, FZero, we havent been riding again for quite a time now.